Hot-rolled high-strength steel with yield strength of 800 MPa and production method thereof

Abstract

The invention provides hot-rolled high-strength steel with yield strength of 800 MPa and a production method thereof. The steel plate comprises the following components by weight: 0.04%-0.07% of C, 0.20%-0.30% of Si, 1.65%-1.85% of Mn, 0-0.015% of P, 0-0.003% of S, 0.25%-0.35% of Ni, 0.20%-0.30% of Cr, 0.20%-0.30% of Cu, 0.20%-0.30% of Mo, 0.05%-0.07% of Nb, 0.010%-0.020% of Ti, 0.03%-0.06% of Als, and the balance of Fe and inevitable impurities. The production method comprises: reheating a casting blank at a temperature of 1200-1250 DEG C, performing rough rolling with a finishing temperature of 1010-980 DEG C; when the rough rolling is finished and the temperature returns to 930 DEG C-950 DEG C, performing finish rolling with a finishing temperature of 830-805 DEG C; cooling after rolling, wherein the cooling is divided into two phases: 1) in the first phase, performing quenching cooling to 300-150 DEG C with a cooling speed of more than 20 DEG C / s; 2) in the second phase, performing slow cooling to room temperature with a cooling speed of less than 30 DEG C / h. The high-strength steel has high yield strength, plasticity, toughness and good weldability; off-line heat treatment after rolling is canceled, which reduces the production cost.

Description

technical field [0001] The invention belongs to the field of metal materials, and in particular relates to a hot-rolled high-strength steel with a yield strength of 800 MPa and good toughness and welding performance and a production method thereof. Background technique [0002] With the development of the world economy, the pressure on resources, environment and energy is increasing day by day. Environmental protection and energy saving are getting more and more attention from the steel industry. The development of high-strength steel with energy saving, high efficiency, long life and excellent performance to meet the needs of the development of key industries in the national economy such as petroleum, coal, chemical industry, electric power, and transportation is also an important way for the iron and steel industry to achieve sustainable development. [0003] High-strength steel currently used in industries such as shipbuilding, pressure vessels, offshore oil platforms, oi...

AI Technical Summary

Problems solved by technology

The carbon equivalent of the steel is high (Ceq=0.713), and the welding performance is poor

In addition, the patent does not provide low-temperature toughness, but its high carbon and silicon content indicates that its low-temperature toughness is also poor

[0006] Publication No. CN 101041879A discloses the patent "Hot-rolled ultra-high-strength martensitic steel and its manufacturing method", which provides a method for producing hot-rolled coils with a yield strength of 860MPa by hot rolling, but this high-strength steel It is produced by ultra-low temperature coiling after hot rolling by a high-power coiler, and can only produce hot-rolled coils with a thickness of 1-4mm

[0007] It can be seen that the production cost of 800MPa high-strength steel by using hot rolling and off-line heat treatment after rolling in the prior art is relatively high; the 800MPa grade steel plate obtained by using high-carbon, high-silicon and high-manganese alloy design has toughness and Welding performance is poor; and the use of ultra-low temperature coiling method to produce or thin-gauge hot-rolled coils requires a high-power coiler and can only produce thin-gauge coils

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